diff --git a/SJBackGRProject/.DS_Store b/SJBackGRProject/.DS_Store
index 061ce00..0851d4c 100644
Binary files a/SJBackGRProject/.DS_Store and b/SJBackGRProject/.DS_Store differ
diff --git a/SJBackGRProject/SJBackGRProject.xcworkspace/xcuserdata/bluedancer.xcuserdatad/UserInterfaceState.xcuserstate b/SJBackGRProject/SJBackGRProject.xcworkspace/xcuserdata/bluedancer.xcuserdatad/UserInterfaceState.xcuserstate
index efbee80..94ba35b 100644
Binary files a/SJBackGRProject/SJBackGRProject.xcworkspace/xcuserdata/bluedancer.xcuserdatad/UserInterfaceState.xcuserstate and b/SJBackGRProject/SJBackGRProject.xcworkspace/xcuserdata/bluedancer.xcuserdatad/UserInterfaceState.xcuserstate differ
diff --git a/SJFullscreenPopGesture.podspec b/SJFullscreenPopGesture.podspec
index 4e1eb46..731b7dc 100644
--- a/SJFullscreenPopGesture.podspec
+++ b/SJFullscreenPopGesture.podspec
@@ -9,7 +9,7 @@
 Pod::Spec.new do |s|
 
   s.name         = "SJFullscreenPopGesture"
-  s.version      = "1.4.1"
+  s.version      = "1.4.2"
   s.summary      = "fullscreen pop gestures."
   s.description  = 'fullscreen pop gesture. System native gestures and custom gestures are free to switch.'
 
diff --git a/SJFullscreenPopGesture/UINavigationController+SJVideoPlayerAdd.m b/SJFullscreenPopGesture/UINavigationController+SJVideoPlayerAdd.m
index c49940b..41eaac0 100644
--- a/SJFullscreenPopGesture/UINavigationController+SJVideoPlayerAdd.m
+++ b/SJFullscreenPopGesture/UINavigationController+SJVideoPlayerAdd.m
@@ -46,7 +46,13 @@ + (void)load {
             SEL swizzledSelector = sel[++ i];
             Method originalMethod = class_getInstanceMethod(nav, originalSelector);
             Method swizzledMethod = class_getInstanceMethod(nav, swizzledSelector);
-            method_exchangeImplementations(originalMethod, swizzledMethod);
+            BOOL added = class_addMethod([self class], originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
+            if ( added ) {
+                class_replaceMethod([self class], swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
+            }
+            else {
+                method_exchangeImplementations(originalMethod, swizzledMethod);
+            }
         }
     });
 }
diff --git a/SJNavigationPopGesture.podspec b/SJNavigationPopGesture.podspec
index 68671a0..e192462 100644
--- a/SJNavigationPopGesture.podspec
+++ b/SJNavigationPopGesture.podspec
@@ -16,7 +16,7 @@ Pod::Spec.new do |s|
   #
 
   s.name         = "SJNavigationPopGesture"
-  s.version      = "1.4.1"
+  s.version      = "1.4.2"
   s.summary      = "fullscreen pop gestures."
 
   # This description is used to generate tags and improve search results.
diff --git a/SJNavigationPopGesture/SJNavigationPopGesture.swift b/SJNavigationPopGesture/SJNavigationPopGesture.swift
index fe0065a..113071e 100644
--- a/SJNavigationPopGesture/SJNavigationPopGesture.swift
+++ b/SJNavigationPopGesture/SJNavigationPopGesture.swift
@@ -67,9 +67,15 @@ public class SJNavigationPopGesture {
         for sel in selArr {
             let originalSelector = sel[0]
             let swizzledSelector = sel[1]
-            let originalMethod = class_getInstanceMethod(cls, originalSelector);
-            let swizzledMethod = class_getInstanceMethod(cls, swizzledSelector);
-            method_exchangeImplementations(originalMethod!, swizzledMethod!)
+            let originalMethod = class_getInstanceMethod(cls, originalSelector)!;
+            let swizzledMethod = class_getInstanceMethod(cls, swizzledSelector)!;
+            let added = class_addMethod(cls, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod))
+            if ( added ) {
+                class_replaceMethod(cls, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
+            }
+            else {
+                method_exchangeImplementations(originalMethod, swizzledMethod)
+            }
         }
     }
 }